I've been listening to my three way active dipole speakers and like a lot of things about it. However the bass department is disappointing. My mid is a 6 inch and bass a 12 inch driver. The bass is also listener position dependant. At about 12 feet from the speakers the low end is 'light'. At 6 feet from the drivers it sounds good with good 'weight' in the low end. Doesn't look like I can solve this with small positional changes of the speakers.
SO, I tried adding a 10 inch ( yech !?) sealed mono sub to it . WOW , it transformed the system. However all is not really well as I have not set the cross over frequency properly. I was just testing a repaired sub amp that I had built for a friend 18 years ago. As expected the bass isn't as nice as the plain dipole at 6 feet ! But it does have weight and is better than the usual boxed speaker bass.
So I'm beginning to feel that I needn't equalise my dipole to go down low with plenty of eq but let the boxed sub take over at some lower frequency.
Anyone been using such a system? I'm sure many have but how about some details about crosover freq/rolloff and listening test results. I feel 60 Hz might be a good point to crossover to keep as much of the dipole sound as possible. This is just gut feeling and not based on any maths or measurements!
Cheers.
SO, I tried adding a 10 inch ( yech !?) sealed mono sub to it . WOW , it transformed the system. However all is not really well as I have not set the cross over frequency properly. I was just testing a repaired sub amp that I had built for a friend 18 years ago. As expected the bass isn't as nice as the plain dipole at 6 feet ! But it does have weight and is better than the usual boxed speaker bass.
So I'm beginning to feel that I needn't equalise my dipole to go down low with plenty of eq but let the boxed sub take over at some lower frequency.
Anyone been using such a system? I'm sure many have but how about some details about crosover freq/rolloff and listening test results. I feel 60 Hz might be a good point to crossover to keep as much of the dipole sound as possible. This is just gut feeling and not based on any maths or measurements!
Cheers.
Depending on the frequency response of all involved drivers, crossover order and room modes, the "real" acoustical crossover point, where the one driver starts to be louder than the other one, may be not the point you dialed into the crossover but lower or higher. This means, what Cal says is the best practical advice 
Yes of course, it always ends up at the ear !
We do need to start some place that 'might' have a good reason .
Well I'll just go ahead with my guesstimate and see how it works out. I did expect a flurry of 'number' suggestions but doesn't look like it .
However I 'feel' that a sealed box sub might work better than a reflex box. Might retain some of the tactile feel.........?
We do need to start some place that 'might' have a good reason .
Well I'll just go ahead with my guesstimate and see how it works out. I did expect a flurry of 'number' suggestions but doesn't look like it .
However I 'feel' that a sealed box sub might work better than a reflex box. Might retain some of the tactile feel.........?
Your question seems to be based on the assumption that dipole bass will always sound better, and that it is a compromise when using monopole, therefore the higher you cross from monopole to dipole, the greater the SQ compromise.
I've found that monopole vs dipole can actually be very difficult to distinguish. With my current Rythmik subs I've found this true - EQ monopole vs open baffle dipole to the same response, they both sound the same (in my room).
An alternative approach is multiple monopoles, as suggested by Geddes.
Coming back to your question. First thing to do is measure! I've found dipoles don't behave exactly as you expect. Find out where they are actually rolling off. If it turns out you need EQ only below 40 Hz, then it would make sense to cross at this point. This would be ideal.
You might also experiment with placement of additional monopole subs - some locations will work better. Ideally you want to be able to measure and use eq.
I've found that monopole vs dipole can actually be very difficult to distinguish. With my current Rythmik subs I've found this true - EQ monopole vs open baffle dipole to the same response, they both sound the same (in my room).
An alternative approach is multiple monopoles, as suggested by Geddes.
Coming back to your question. First thing to do is measure! I've found dipoles don't behave exactly as you expect. Find out where they are actually rolling off. If it turns out you need EQ only below 40 Hz, then it would make sense to cross at this point. This would be ideal.
You might also experiment with placement of additional monopole subs - some locations will work better. Ideally you want to be able to measure and use eq.
Paul you hit the nail on the head !!
Multiple monopoles is out of the question for me. I'm on the last thread with respect to being thrown out of home ( due to too much equipment ). More subs and I definitely will have to find a new home !
Yes..... measure..... . measure, measure ! My 12 inch sub measures quite well but doesn't sound as I think they should after looking at ( the graph of ) what I measured.
A lower transition frequency would be ideal. I will work on that sometime this week. Weekends are becoming too busy for me . I prefer to keep eq at a minimum if possible.
Haven't done anything for the last few days with temperatures rising every day. Today it was 40 deg C at mid day ! Not to mention the accompanying high humidity ! Couldn't be worse.
Sweat , sweat , sweat all the time. Can't have aircon all over the place.
Do you realise I was challenging the idea, not reinforcing it?
Open baffle bass involves either a major reduction in output, or a big increase in cost.
Consider this. You start with one 10" monopole sealed sub. To match the output you use four of the same in a H frame and give up room gain therefore a lot of extension. Four times the cost!
Now instead you decide to try four monopoles. You'll probably get a decent smooth response (perhaps even better). Perhaps even use smaller drivers.
Do you get complaints based on how many subs, or based on how loud you play them?
If you find that your subs sound way better as open baffle, then this suggests there is a problem that isn't related to dipole vs monopole. Monopole can match the sound quality of a dipole with less drivers, less cost and more output.
Of course, if you still want to do OB, I say go for it. However, don't do it thinking you can't achieve the SQ any other way.
While you have you AC on, over here in Australia we are starting to put our heaters on. It's winter!
Just one question:
If you discovered that you were able to get a monopole to sound as good as an OB dipole, would you still be interested in dipole bass?
Hi Paul,
I meant exactly what I said .However it does look unclear what I meant.
I understood that you were challenging my 'idea' and I meant that I figured you understood that part of it ! You don't obviously subscribe to my ( current ) point of view.
Well at the moment it "appears" to me that the OB bass sounded less boomy ( at times !) and clearer than my boxed speakers. Now there could be many factors that could cause that. First of all the drivers are not the same. But I did get the impression that OB bass had a tactile feel to it that I couldn't get in my boxed sub. Maybe that my boxed sub isn't good ?
It's a sealed unit with a Qtc of about 0.6 and low Fc ( can't remember the figure ).
I've done OB with boxed bass crossed over over at 600Hz. Sounded good but not quite the same as a full range OB. But there again no point going into all this as there are so many variables involved in those units that I tried.
I'll just focus on what I'm trying now. My biggest problem being that I don't have enough time to check all possibilities.
Answer to your question about using a monople if it is as good as a dipole. The answer is YES of course. In fact I HOPE it will turn out that way . Like you said , more spl for the same power input , smaller drivers , smaller baffle etc. For the same performance I'd be crazy to use an OB sub !
Cheers.
I meant exactly what I said .However it does look unclear what I meant.
I understood that you were challenging my 'idea' and I meant that I figured you understood that part of it ! You don't obviously subscribe to my ( current ) point of view.
Well at the moment it "appears" to me that the OB bass sounded less boomy ( at times !) and clearer than my boxed speakers. Now there could be many factors that could cause that. First of all the drivers are not the same. But I did get the impression that OB bass had a tactile feel to it that I couldn't get in my boxed sub. Maybe that my boxed sub isn't good ?
It's a sealed unit with a Qtc of about 0.6 and low Fc ( can't remember the figure ).
I've done OB with boxed bass crossed over over at 600Hz. Sounded good but not quite the same as a full range OB. But there again no point going into all this as there are so many variables involved in those units that I tried.
I'll just focus on what I'm trying now. My biggest problem being that I don't have enough time to check all possibilities.
Answer to your question about using a monople if it is as good as a dipole. The answer is YES of course. In fact I HOPE it will turn out that way . Like you said , more spl for the same power input , smaller drivers , smaller baffle etc. For the same performance I'd be crazy to use an OB sub !
Cheers.
Now I think we understand each other.
Following your current track ... what makes sense is crossing at a point which is determined by your room. You'd want some measurements of monopoles placed in different locations, and see where you can find room modes in the response, and where room gain occurs. The Linkwitz approach is to find where the room modes stop being an issue, which might be 40 Hz, and then monopole below this point. The theory goes that most rooms will have a modal range 40 - 200 Hz.
On the topic of modes, I've noticed when playing around with one room mode simulator that dipoles aren't necessarily better in this regard. I'd be curious to see actual measured examples of this.
By the way, I'm a huge fan of open baffle (my speakers are open baffle), but I prefer to use it where it gains advantages you can't get any other way. The midrange is magnificent. Large sweet spot, no box coloration, greater sound stage depth and width, and they do a much better disappearing act. And I also find I can do away with the centre speaker where I couldn't get away with this with box speakers.
I had my old subs (AE speakers AV12) I H frames and found they sounded much better than sealed box. When I got my current subs (2 Rythmik kits), I did a test. One in a H frame, the other sealed box. I set up eq to give them the same response, so I was comparing sound quality differences only. I was able to do a quick AB comparison. I selected a song which is a good test, with acoustic double bass, and kept switching from one to the other.
Verdict? The difference was so small it was almost imaginary. I thought at times I could hear something, but I can't say either was better. Certainly I was ready to ditch the open baffle idea for the bass.
How does the Rythmik take away the advantage?
Here's my guess.
Once you get a monopole and a dipole to the same response curve, how are they different? The dipole has no air spring and the result is low Q, and this is great for control and time domain performance. Also you are not trying to store the energy of the rear wave inside the box, which you can never achieve perfectly. The box will vibrate and the bass inside will also afftect the movement of the cone, re-radiating it back into the room. Most diyers think about the box, but in reality the cone itself deserves more attention as it is actually designed to move and create sound. As such it is vulnerable to the rear wave being re-radiated. It's ability to reject this influence is related to its damping (Qts).
As I see it these are the two key differences. If we remove the velocity source/room mode issue, then IB has the same performance advantages over a sealed box.
Those two areas happen to be two in which the Rythmik excels due to the servo, and they are both due to not very well known fact that the servo gives an effective Q of 0.3 much lower than the typical 0.7 with most sealed subs, or 0.5 for those who live with a bigger box. The low Q means it is better able to reduce re-radiation, and also achieves very good transient performance.
If you are using other drivers in a sealed box, then I don't know what your result will be. I suspect that you will find that you can get the same SQ as your OB with any of these:
IB (if the drivers are good quality)
sealed servo subs
horn loaded
Following your current track ... what makes sense is crossing at a point which is determined by your room. You'd want some measurements of monopoles placed in different locations, and see where you can find room modes in the response, and where room gain occurs. The Linkwitz approach is to find where the room modes stop being an issue, which might be 40 Hz, and then monopole below this point. The theory goes that most rooms will have a modal range 40 - 200 Hz.
On the topic of modes, I've noticed when playing around with one room mode simulator that dipoles aren't necessarily better in this regard. I'd be curious to see actual measured examples of this.
By the way, I'm a huge fan of open baffle (my speakers are open baffle), but I prefer to use it where it gains advantages you can't get any other way. The midrange is magnificent. Large sweet spot, no box coloration, greater sound stage depth and width, and they do a much better disappearing act. And I also find I can do away with the centre speaker where I couldn't get away with this with box speakers.
I had my old subs (AE speakers AV12) I H frames and found they sounded much better than sealed box. When I got my current subs (2 Rythmik kits), I did a test. One in a H frame, the other sealed box. I set up eq to give them the same response, so I was comparing sound quality differences only. I was able to do a quick AB comparison. I selected a song which is a good test, with acoustic double bass, and kept switching from one to the other.
Verdict? The difference was so small it was almost imaginary. I thought at times I could hear something, but I can't say either was better. Certainly I was ready to ditch the open baffle idea for the bass.
How does the Rythmik take away the advantage?
Here's my guess.
Once you get a monopole and a dipole to the same response curve, how are they different? The dipole has no air spring and the result is low Q, and this is great for control and time domain performance. Also you are not trying to store the energy of the rear wave inside the box, which you can never achieve perfectly. The box will vibrate and the bass inside will also afftect the movement of the cone, re-radiating it back into the room. Most diyers think about the box, but in reality the cone itself deserves more attention as it is actually designed to move and create sound. As such it is vulnerable to the rear wave being re-radiated. It's ability to reject this influence is related to its damping (Qts).
As I see it these are the two key differences. If we remove the velocity source/room mode issue, then IB has the same performance advantages over a sealed box.
Those two areas happen to be two in which the Rythmik excels due to the servo, and they are both due to not very well known fact that the servo gives an effective Q of 0.3 much lower than the typical 0.7 with most sealed subs, or 0.5 for those who live with a bigger box. The low Q means it is better able to reduce re-radiation, and also achieves very good transient performance.
If you are using other drivers in a sealed box, then I don't know what your result will be. I suspect that you will find that you can get the same SQ as your OB with any of these:
IB (if the drivers are good quality)
sealed servo subs
horn loaded
Some results
I measured my open baffle response and found that it starts rolling off by about 60Hz in my listening room. The bass eq is modest at about 8dB at 40 Hz.
I left the OB as it is and added a 10 inch sub with a 12dB LPF set at 60Hz. I made a variable unit with a fc variable from about 30 Hz to 100 Hz. The 60 Hz setting does seem to be fine. I need to measure the response of the new set up.
On music it does sound very nice and fills up the lower frequencies very well. Bass impact is very good. Deep and tight. Better than a full range box but probably slightly short of what I had heard with an OB using a 15 inch bass driver. Still, this configuration is very easy to live with especially because it needs a smaller power amp for the bass and the sub is so small.
I find that I might need to add a HPF for the OB bass driver to keep out the inaudible low end which makes it flap the cone around a lot at high volume. I think I might have damaged one of the OB bass drivers when some unexpected LF content made the coil smash into the frame several times causing some very alarming noises.
I measured my open baffle response and found that it starts rolling off by about 60Hz in my listening room. The bass eq is modest at about 8dB at 40 Hz.
I left the OB as it is and added a 10 inch sub with a 12dB LPF set at 60Hz. I made a variable unit with a fc variable from about 30 Hz to 100 Hz. The 60 Hz setting does seem to be fine. I need to measure the response of the new set up.
On music it does sound very nice and fills up the lower frequencies very well. Bass impact is very good. Deep and tight. Better than a full range box but probably slightly short of what I had heard with an OB using a 15 inch bass driver. Still, this configuration is very easy to live with especially because it needs a smaller power amp for the bass and the sub is so small.
I find that I might need to add a HPF for the OB bass driver to keep out the inaudible low end which makes it flap the cone around a lot at high volume. I think I might have damaged one of the OB bass drivers when some unexpected LF content made the coil smash into the frame several times causing some very alarming noises.
Attachments
A small note on some changes. I removed the Peerless 12 inch as one driver was damaged ( torn spider !) .
Put in a Delta15A . A direct replacement with only level matching at about 300Hz produced grossly inferior sound compared to the Peerless. The sound also got very 'cuppy' .
This of course is not a very fair comparison as the crossover would also have to be modified to suit the new driver.
But I didn't expect it to sound SO bad !So looks like the Delta15A has some nasties in the lower mids that need to be attended to ?
Back to experimenting again.
OB can be very difficult to get right without the proper drivers.
I wonder how many actually get round to measuring the frequency response of their OB implementation. For some the measured response might come as a shock ?
Put in a Delta15A . A direct replacement with only level matching at about 300Hz produced grossly inferior sound compared to the Peerless. The sound also got very 'cuppy' .
This of course is not a very fair comparison as the crossover would also have to be modified to suit the new driver.
But I didn't expect it to sound SO bad !So looks like the Delta15A has some nasties in the lower mids that need to be attended to ?
Back to experimenting again.
OB can be very difficult to get right without the proper drivers.
I wonder how many actually get round to measuring the frequency response of their OB implementation. For some the measured response might come as a shock ?
he 12 inch Peerless ( 831857 ) was used in the OB panel . The ( mono ) sub was a 10 inch Peerless ( 830146 ) . I replaced the 12 inch on the OB with the 15 inch Delta15A .
Pic attached. Will be running fresh tests on the system today ( if possible ) to determine what to modify in the crossover. Right now it's unlistenable .
Listening position is about 12 feet from the speakers. Bass is light at this position. Low end comes up quite a bit at about 8 feet from the speakers. The sub is not required here.
With the sub working the sound is fine at 12 feet.
You are right. It needs less boost than expected. I think getting it right is very time consuming.
Cheers.
Pic attached. Will be running fresh tests on the system today ( if possible ) to determine what to modify in the crossover. Right now it's unlistenable .
Listening position is about 12 feet from the speakers. Bass is light at this position. Low end comes up quite a bit at about 8 feet from the speakers. The sub is not required here.
With the sub working the sound is fine at 12 feet.
You are right. It needs less boost than expected. I think getting it right is very time consuming.
Cheers.
Attachments
I have not heard a system that has been set with Ultracurve so I cannot comment on how it sounds. However I have found the ear to accept reasonable amounts of deviation from a flat curve and still sound very acceptable and nice. That way it also avoids extra processing . I'm inclined to believe that less processing is always better .
There are pro's and con's but each one to his own system I guess.
There are pro's and con's but each one to his own system I guess.
Getting it flat is just the starting point, so that I can then create the curve that I want. Staying with flat is very unsatisfying.
I've been able to work out what I find sounds best for most things. And I also create a level dependent loudness contour, so the bass sounds right at all volumes.
In theory I agree - less is better. However, in the end the result I get with it is better.
I've been able to work out what I find sounds best for most things. And I also create a level dependent loudness contour, so the bass sounds right at all volumes.
In theory I agree - less is better. However, in the end the result I get with it is better.
The Peerless 831857 drive is great ....my opinion. Only thing I dislike about it is that the suspension, particularly the spider is not OK. It sags with age even when kept vertical. Something to do with unequal forces in the suspension system. I wouldn't waste time figuring that . But certainly not a driver that can be used for very long !
I trust the new driver replacing this has overcome these defects.
Sounds very good ( the 831857) even up to 600Hz which I had used with a pair of B&G planar's. There are better drivers of course with most being far more expensive.
We spend lots of time listening to music with peaks of 104dB at 12 feet from the speakers and two or three bottles of fairly strong wine. Usually on Saturdays with Sunday to recover !
So it's quite loud but not deafening. So I've been forced to become a bootlegger too !
We need lot's of hooch at affordable prices -- DIY again !
Cheers.
I trust the new driver replacing this has overcome these defects.
Sounds very good ( the 831857) even up to 600Hz which I had used with a pair of B&G planar's. There are better drivers of course with most being far more expensive.
We spend lots of time listening to music with peaks of 104dB at 12 feet from the speakers and two or three bottles of fairly strong wine. Usually on Saturdays with Sunday to recover !
So it's quite loud but not deafening. So I've been forced to become a bootlegger too !
We need lot's of hooch at affordable prices -- DIY again !
Cheers.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.